Bolts r.01.0

Description

Preloaded bolts are widely used in the assembly of unthreaded components and they are composed of two elements: the screw and the nut.
The joined parts are drilled and the common hole between the two components is crossed by a screw which is coupled to a nut on the opposite side.
The holes in the components shall not be threaded and must allow the free movement of the screw.

This software, for an "ideal" friction grip type bolted connection, preloaded with a tightening torque and loaded with external tensile and shear forces, calculates:

• the tightening torque,
• the opening proof of the assembly,
• the static and fatigue proof of the bolt,
• the slip proof of the joined components,
• the maximum pressure under torqued head or nut.

We neglect:

• assembling errors,
• manufacturing and dimensional tolerances,
• plastic deformations,
• eccentricity of the external loads.

The maximum tightening torque C_max is calculated so that the equivalent stress during the preloading phase is equal to the 85% of the yield stress of the screw.
The bolt friction coefficient µ takes into account the friction in the threads and under the torqued head or nut.
The thread of the bolt is "metric ISO".
In service a decrease of the shear stress due to the tightening torque is supposed equal to 50%.
The characteristic fatigue strength of the bolt is calculated for 2·10⁶ cycles.
External loads are considered applied in line with the bolts and in the middle of the plates.

To calculate the bolt, fill the input forms with:

• the characteristics of the bolt,
• the characteristics of the plates,
• the external loads (tension and shear).

Click on the "Run" button and the software calculates:

• the tightening torque (maximum and minimum) and the related preloading force (maximum and minimum),
• the opening proof of the assembly,
• the static and fatigue proof of the bolt,
• the slip proof of the joined components,
• the maximum pressure under torqued head,
• the stiffness of the bolt and the stiffness of the connected parts.